ORA-16179: incremental changes to "log_archive_dest_1" not allowed with SPFILE

SQL> archive log list
Database log mode              No Archive Mode
Automatic archival               Disabled
Archive destination              USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence   1
Current log sequence           2

SQL> alter system set log_archive_dest_1='/u01/prod/arch' ;
alter system set log_archive_dest_1='/u01/prod/arch'
*
ERROR at line 1:
ORA-32017: failure in updating SPFILE
ORA-16179: incremental changes to "log_archive_dest_1" not allowed with SPFILE


When you move from the old log_archive_dest to the "new" log_archive_dest_<n>, a common mistake is missing the required string "location=" or "service=". 
So you need to say,

log_archive_dest_1='LOCATION=/u01/prod/arch'


SQL> alter system set log_archive_dest_1='LOCATION=/u01/prod/arch' scope=both;

System altered.

SQL> shut immediate
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup